Csaba

I just measured the voltage at the pump. There is a huge voltage drop as the relay cycles. The fluctuation is almost a full 12V - Peak ~12.3V and trough 0,5V ....

Some feedback ... I fired up the circuit and connected a voltmeter as suggested. I ran it for approx 1 minute and the voltage only fluctuated between 12,29V and 12,3V, no peaks or troughs and virtually no loss of voltage for the duration of operation ... As mentioned above, the load is a 12V Shureflo water pump which when the circuit is connected, pumps water from a sump to a pressurised (electric) shower head. If I replace this shower head with an unpressurised free flowing head and fire up the circuit, the relay does not clatter away and the whole system operates uninterrupted ... It therefore appears that if the water pump operates under higher pressure it seems to require more power and this is where the relay starts clattering. Hope this makes sense ...

Thanks for the input gents, even though the discussion is now a little above my pay grade... Interestingly, whilst the cover of the relay has 30A-AC imprinted on it, the covering over the coil has 'DC12V'. Not sure if the two descriptors are related. It does seem like a DC relay ... To my original question though, could you please explain what would cause the relay to clatter away once the citcuit is fired up? I am also considering bypassing the relay altogether as I'm not sure why it was installed in the first place. Would this be advisable, or not?

Good question. I'm not sure. The system was originally set up by someone else. I guess the relay might have been inserted for the low voltage battery and the higher voltage solar set up ...?

Pump is not adjustable. It is a Shureflo diaphragm pump 2088-443-144

Hi. It is only a relay, not a pressure relay. The exact model is Rhomberg code: #JQX-50F 30A-AC.

Hi. I'm new to this forum and most things electrical, so apologies at the outset if any of the issues raised sound a little stupid ... I'm busy with a garage project. I have a 12v 102Ah deep cycle battery feeding into a Victron BlueSolar charge controller (MPPT 75 l 15) then into a Shureflo 12V water pump through a Rhomberg 30amp power relay. The water is pumped to a Speedheat 3,5KW electric shower head. Although I haven't connected it as yet, I also have an Enersol 260W solar panel feeding into the charge controller. The issue that I'm experiencing is that the once I fire up the circuit the pump fills up the PVC pipes with water (from a sump) leading to the showerhead - the power relay starts to click away continuously opening and closing the circuit .... The pump capacity (45PSI at free flow) and the showerhead pressure (min 50kPa - max 800kPa) appear to compatible. If I then replace the showerhead with a free flow shower head, the system runs smoothly and the relay operates as expected - switches on and stays on. What is causing the relay to run intemittently? Is it power related; is it pressuring related even though the pump capacity and the showerhead pressure are compatible?; is it a wiring related or is there something else I should be looking at? Dr Google solves many of my problems but he has let me down on this one. I really would appreciate a simple dumbed-down response advising what to check, adjust, change, etc. Many thanks.